The invention relates to an emergency running ring of rubber or another elastomer for use with tubeless air-inflated tires for commercial vehicles mounted on flat-base rims. The ring is formed with several radial bores for the admission of air, and a plurality of circumferential hollow cavities filled with a lubricant and sealed. The cavities are opened only in the case of loss of air, which results in the tire casing pressing on the emergency running ring by means of lever action, thereby releasing the lubricant for the purpose of reducing friction between the ring and the tire.
An emergency running ring of this type is known and described in U.S. application Ser. No. 97,414 of Hermann Stein, filed Nov. 26, 1979, now U.S. Pat. No. 4,295,509 issued Oct. 20, 1981. According to this application, circumferential hollow cavities are arranged on both sides of the emergency running ring and filled with a lubricant. The cavities are sealed by means of sealing lips which fit against the inner wall of the tire and are pressured against the inner wall by the air pressure prevailing in the tire. In a further known emergency running ring, the cavities filled with lubricant are arranged between the outer side and a central, circumferential groove of the emergency running ring. The sealing lips, together with the edge zones of the emergency running ring, always seal one of the lubricant outlet channels leading from the cavity into the inner space of the tire, by means of a lateral prestress generated in the course of the mounting of the tire.
In both cases, the opening of the cavities filled with lubricant is effected by a certain lever action resulting from the emergency. Actual practice has shown, however, that due to the higher centrifugal force in the tire at high velocities, the lubricant may be released to a varying degree even prior to the occurrence of an emergency.